Roof Drain, Gutter Outlet & Cowl Waterproofing in Saudi Arabia

Why the outlet is so often the source of the leak

The connection between the gutter bed and the outlet or cowl is one of the most awkward details on any roof. It changes shape from flat to round, it is usually held by rivets, screws or a ring of sealant, and it sits in the wettest spot of all. That sealant ring cracks in the summer heat, and on coastal sites such as Jubail and Dammam the steel around the hole rusts from the edge outwards. The result is a leak directly above the downpipe, often mistaken for a problem with the pipe itself.

Dust makes it worse. After a sandstorm, silt settles in the outlet and slows the flow, so water ponds around the drain and presses on the weakest part of the seal. When the heavy winter rain finally arrives, the whole roof drains towards that one point at once. Sealing the outlet properly, and keeping it clear, protects not only the drain but the gutter and ceiling around it.

Warning signs at drains and outlets

• Water running down the outside of a downpipe inside the building
• Ceiling or insulation stains centred on an outlet position
• Cracked sealant or rust around the rim of the cowl
• Water ponding around the drain long after the rain stops
• Outlets repeatedly blocked with sand and debris

How we waterproof roof drains and cowls

1. Inspect every outletOur engineer checks each drain, cowl and outlet on the roof, including hidden rust at the rim, and records it in the photo report.
2. Clear and cleanSand, silt and debris are removed from the outlet, and the surrounding area is cleaned of failed sealant and loose rust.
3. Form the EPDM into the drainThe membrane is cut to fit the outlet and dressed down into the cowl, so water flows over rubber rather than over a joint.
4. Bond to the surrounding surfacePromax Bonding Adhesive fixes the EPDM to the outlet and to the gutter bed or concrete around it, leaving no gap at the transition.
5. Check the flow pathThe finished outlet is checked for adhesion and free drainage, then photographed for your records.

Materials & workmanship

• 1.2 mm EPDM membrane formed into drains on both metal and concrete roofs
• Promax Bonding Adhesive, rated for surface temperatures up to 120 °C
• Can be combined with an EPDM gutter lining for a continuous path from gutter to downpipe
• Written survey report with photos of every outlet before work starts

Photos from ETCE projects

Site photos from ETCE projects in Saudi Arabia and Bahrain. Tap to enlarge.

Frequently asked questions